[libc-commits] [libc] [libc][arm] implement setjmp/longjmp (PR #93220)

[Roland McGrath via libc-commits]

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@@ -0,0 +1,31 @@
+
+//===-- Implementation of longjmp -----------------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+#include "src/setjmp/longjmp.h"
+#include "src/__support/common.h"
+#include "src/__support/macros/properties/architectures.h"
+
+#if !defined(LIBC_TARGET_ARCH_IS_ARM)
+#error "Invalid file include"
+#endif
+
+namespace LIBC_NAMESPACE {
+
+[[gnu::naked]]
+LLVM_LIBC_FUNCTION(void, longjmp, (__jmp_buf * buf, int val)) {
+  asm("ldm.w r0!, {r4, r5, r6, r7, r8, r9, r10, r11, r12, lr}\n\t"
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frobtech wrote:

I think the norm is to use `__asm__`.  Consider using a raw string with natural newlines.

The `!` is not really useful here, since `r0` is not used again.

The syntax allows `{r4-r12, lr}` which IMHO is more readable.

It's unusual to use the `.w` suffix rather than letting the assembler decide what encoding to use.  I'd just use `ldm r0, {r4-r12, lr}` here.

https://github.com/llvm/llvm-project/pull/93220